The Myology of Chimpanzee and Baboon. 441 
in a penniform manner into a tendon which extends nearly the 
whole length of the muscle. One third of the way from its origin 
to ius insertion, the tendon lies on its radial aspect, the fibers being 
inserted upon the ulnar side of the tendon. Beyond this, other 
fibers arise from the radial side of the tendon, and those on the 
ulnar side twist around so that the tendon is on the ulnar side of 
the belly. This gives the musclea digastric appearance. The ten- 
don is inserted into the base of the second phalanx, as is the case 
inman. All four bellies are inserted into their respective digits in 
the same manner. Two fasciculi are given off at the poiat 
where this belly is twisted, to join the belly for the third digit. 
B. The division for the third digit arises (a) from the tendinous 
sheath of the flexor carpi radialis, superficially to the origin of the 
first head, by three separate divisions, each 1 cm. wide, at points 
2, 4. and 5 em. respectively from the insertion of the flexor carpi 
radialis into the internal condyle of the humerus; (6) along the 
oblique line of the radius from a point 4 cm. from the distal end 
of the bone to a point 6 em. from its proximal end, and from the 
brachial fascia neighboring this line. The bundles of the proxi- 
mal origin continue down the arm loosely joined. The radial 
head joins this tendon obliquely on its radial border. This whole 
belly is superficial to the first one, and lies on its radial side. 
C’. The division for the fourth digit arises (1) most superficially 
from the tendinous sheath of the flexor carpi radialis by three 
strap-like divisions (a) 5 em. distal to the external condyle, (b) 
more distal, 1 em. broad, (c) distal to (6) 2 cm. broad; a and b unite 
but c does not join the other two for two thirds of the way down 
the arm: and (2) from the intermuscular septum between it and the 
flexor carpi ulnaris, near its insertion into the internal condyle. 
All these fibers are inserted in a penniform manner upon the inner 
surface of the tendon, which extends half way up the arm. 
D. The division for the fifth digit arises from the intermuscular 
septum between it and the flexor carpi ulnaris, at a point 6 em. 
from its origin. This division is very small and is entirely covered 
by the flexor-carpi ulnaris. The tendon islong and slender. From 
this it will be seen that the independence of the origins is well 
marked, and, with one exception, there is not the slightest con- 
nection between any of the main divisions. 
